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Unformatted text preview: Human Impacts Human Outline Outline Water Pollution Air Pollutants Acid deposition Ozone Thinning Ozone Deforestation Desertification Water Use and Scarcity Most of Earth’s water is too salty for human consumption Desalinization is expensive and requires energy Aquifer Problems Aquifer Irrigation of crops is the main use of freshwater Groundwater provides most of the water used by humans in U.S.
2% of U.S. groundwater is polluted Negative Effects of Irrigation Negative Salinization, mineral buildup in soil Elevation of the water table and Elevation waterlogging waterlogging Depletion of aquifers Water Pollutants Water Sewage Animal wastes Fertilizers Pesticides Industrial chemicals Radioactive material Disease Causing Agents Sediments Excess heat (thermal pollution) Excess Sources Sources Point vs. Non-Point Point: the source can be tracked down be Point sources (e.g., factories, sewage treatment plants, mines, oil wells, oil tankers) oil Non-Point Sources Non-Point Excess fertilizers, herbicides, and insecticides from Excess agricultural lands and residential areas; agricultural Oil, grease, and toxic chemicals from urban runoff Oil, and energy production; and Sediment from improperly managed construction Sediment sites, crop and forest lands, and eroding streambanks; sites, Salt from irrigation practices and acid drainage from Salt abandoned mines; abandoned Bacteria and nutrients from livestock, pet wastes, and Bacteria faulty septic systems faulty
http://www.epa.gov/owow/nps/qa.html Continued Continued
• Nonpoint source water pollution from agriculture Nonpoint agriculture is largest source of water pollution in the U.S. (64% of pollutants into streams & 57% of pollutants entering lakes) pollutants
Example Huge open-air waste lagoons, often as big as several football fields, are prone to leaks and spills. In 1995 an eight-acre hog-waste lagoon in North Carolina burst, spilling 25 million gallons of manure into the New River. The spill killed about 10 million fish and closed 364,000 acres of coastal wetlands to shellfishing. NRDC Garbage Garbage Ocean of Garbage Video Air Pollutants Air Carbon oxides Sulfur oxides Nitrogen oxides Volatile organic compounds Photochemical oxidants Suspended particles Industrial Smog Industrial Gray-air smog Forms over cities that burn large amounts of Forms coal and heavy fuel oils; mainly in developing countries countries Main components are sulfur oxides and Main suspended particles suspended Photochemical smog Photochemical Brown-air smog Forms when sunlight interacts with components from automobile exhaust Nitrogen oxides are the main culprits Hot days contribute to formation
cool air warm inversion air cool air Health Effects Health Irritations of the eyes and skin Respiratory System Asthma, Emphysema Lung Cancer Allergic reactions Acid Deposition Acid Affects much of eastern Affects North America Caused by the release of Caused sulfur and nitrogen oxides oxides Coal-burning power Coal-burning plants and motor vehicles are major sources sources Ozone Thinning Ozone In early spring and In summer ozone layer over Antarctica thins over
South America Seasonal loss of ozone Seasonal is at highest level ever recorded recorded
Antarctica Result of CFC’s, Result methyl compounds methyl
Ozone Change Effect of Ozone Thinning Effect Increased amount of UV Increased radiation reaches Earth’s surface surface UV damages DNA and UV negatively affects human health health UV also affects plants, lowers UV primary productivity primary Protecting the Ozone Layer Protecting CFC production has been halted in developed CFC countries, will be phased out in developing countries Methyl bromide will be phased out Even with bans it will take more than 50 years Even for ozone levels to recover for Deforestation Deforestation Removal of all trees 38 million acres logged each year Wood is used for fuel, lumber Land is cleared for grazing or crops Regions of Deforestation Regions Rates of forest loss are greatest in Brazil, Rates Indonesia, Mexico, and Columbia Indonesia, Highly mechanized logging is proceeding in Highly temperate forests of the United States and Canada Canada Tropical Deforestation Effects of Deforestation Effects Loss of biodiversity Increased leaching and soil erosion Increased flooding and sedimentation of Increased downstream rivers downstream Regional precipitation declines Possible amplification of the greenhouse Possible effect effect Reversing Deforestation Reversing Non-profits and government agencies Practical Measures
Smokeless wood stoves Smokeless Planting trees Improve recycling technology CUT DOWN ON USE! Desertification Desertification Conversion of large tracts of grassland to desert-like Conversion conditions Conversions of cropland that result in more than 10 Conversions percent decline in productivity percent Ongoing Desertification Ongoing Sahel region of Africa is undergoing rapid Sahel desertification desertification Causes are overgrazing, overfarming, and Causes prolonged drought prolonged One solution may be to substitute native One herbivores for imported cattle herbivores ...
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- Spring '08